The tight-binding model study of the role of electron occupancy on the ferromagnetic gap in graphene-on-substrate

Abstract

We propose here a theoretical model for graphene in its ferromagnetic phase. The Hamiltonian describes electron hoppings up-to-third-nearest neighbours for graphene-on-substrate. The sub-lattice coulomb interactions within mean-field approach involve the total electron occupancy and ferromagnetic magnetisations (FMs). The temperature dependent ferromagnetic magnetisation and hence, the ferromagnetic gap are derived from the electron Green's functions and are solved self-consistently. The result shows that the magnitude of the ferromagnetic gap and the critical coulomb interaction strongly depend on total electron occupancy. The critical coulomb interaction decreases with increase of electron occupancy and the vice-versa.